Читать книгу Principles of Virology - Jane Flint, S. Jane Flint - Страница 190

In addition to the capsids described previously, many virus particles possess an envelope formed by a viral protein-containing membrane that is derived from the host cell. However, viral envelopes vary considerably in size, morphology, and complexity, and they differ in lipid composition, the number of proteins they contain, and their location. The membranes form the outermost layer of enveloped animal viruses, but in some bacteriophages and archaeal viruses the membrane lies beneath an icosahedral capsid (Box 4.8). Typical features of viral envelopes and their proteins are described in the next section, to set the stage for consideration of the structures of envelope proteins and the various ways in which they interact with internal components of the virion.